title: Impact analysis of the discontinuation of reimbursement: the case of oral contraceptives.
abstract: BACKGROUND
  We studied the impact of suspending oral contraceptive (OC) reimbursement in the Netherlands for women >21 years starting 1 January 2004. Discontinuation and switching patterns and the time course of the policy intervention's effects were determined.
  
  
  METHODS
  The intervention cohort contained OC users on 1 January 2004; the control cohort users on 1 January 2003. Follow-up duration was 1 year. Discontinuation and switching patterns were assessed using relative risks (RR). Weekly refill fractions were calculated to determine the time course of the policy effects.
  
  
  RESULTS
  Our intervention cohort contained 434,917 OC users; the control cohort 489,904 users. When we excluded patients not affected by the policy intervention (i.e., all patients younger than 20 years), discontinuation rates were 15.3% (intervention cohort) and 12.3% (control cohort) (RR=1.24; 95% CI=1.23-1.26) and increased with age. Switching to cheaper OCs was greatest in the intervention cohort, particularly in the 40- to 44-year age group. Differences in cumulative refill fractions showed large variation over time.
  
  
  CONCLUSIONS
  The OC reimbursement intervention led to an increase in the discontinuation rate of 24%. The effect increased with older age groups. Considering the time course of effects of policy interventions is of critical importance.
authors.affiliation: Faculty of Science, Division of Pharmacoepidemiology and Pharmacotherapy, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3508 TB Utrecht, The Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: Stolk
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schneeweiss
authors.forename: Hubert G M
authors.initials: HG
authors.lastname: Leufkens
authors.forename: Eibert R
authors.initials: ER
authors.lastname: Heerdink
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D016022:Case-Control Studies; D015331:Cohort Studies; D003268:Contraception Behavior / Q000706:statistics & numerical data*; D003271:Contraceptive Agents, Female / Q000191:economics* / Q000627:therapeutic use; D003276:Contraceptives, Oral / Q000191:economics* / Q000627:therapeutic use; D005260:Female; D006291:Health Policy; D006801:Humans; D007349:Insurance, Health, Reimbursement / Q000191:economics* / Q000706:statistics & numerical data; D009426:Netherlands; D010352:Patient Dropouts / Q000706:statistics & numerical data; D017891:Pharmacoepidemiology
chemical_list: D003271:Contraceptive Agents, Female; D003276:Contraceptives, Oral